linux-kernel - [PATCH v2 17/22] KVM: nSVM: Report interrupts as allowed when in L2 and exit-on-interrupt is set

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Date:   Sat, 25 Apr 2020 03:01:49 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     wei.huang2@....com, cavery@...hat.com, vkuznets@...hat.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Oliver Upton <oupton@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v2 17/22] KVM: nSVM: Report interrupts as allowed when in L2 and exit-on-interrupt is set

Report interrupts as allowed when the vCPU is in L2 and L2 is being run with
exit-on-interrupts enabled and EFLAGS.IF=1 (either on the host or on the guest
according to VINTR).  Interrupts are always unblocked from L1's perspective
in this case.

While moving nested_exit_on_intr to svm.h, use INTERCEPT_INTR properly instead
of assuming it's zero (which it is of course).

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/svm/nested.c |  5 -----
 arch/x86/kvm/svm/svm.c    | 23 +++++++++++++++++------
 arch/x86/kvm/svm/svm.h    |  5 +++++
 3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 226d5a0d677b..a7a3d695405e 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -805,11 +805,6 @@ static void nested_svm_intr(struct vcpu_svm *svm)
 	nested_svm_vmexit(svm);
 }
 
-static bool nested_exit_on_intr(struct vcpu_svm *svm)
-{
-	return (svm->nested.intercept & 1ULL);
-}
-
 static int svm_check_nested_events(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4e284b62d384..0bbb2cd24eb7 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3114,14 +3114,25 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct vmcb *vmcb = svm->vmcb;
 
-	if (!gif_set(svm) ||
-	     (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK))
+	if (!gif_set(svm))
 		return true;
 
-	if (is_guest_mode(vcpu) && (svm->vcpu.arch.hflags & HF_VINTR_MASK))
-		return !(svm->vcpu.arch.hflags & HF_HIF_MASK);
-	else
-		return !(kvm_get_rflags(vcpu) & X86_EFLAGS_IF);
+	if (is_guest_mode(vcpu)) {
+		/* As long as interrupts are being delivered...  */
+		if ((svm->vcpu.arch.hflags & HF_VINTR_MASK)
+		    ? !(svm->vcpu.arch.hflags & HF_HIF_MASK)
+		    : !(kvm_get_rflags(vcpu) & X86_EFLAGS_IF))
+			return true;
+
+		/* ... vmexits aren't blocked by the interrupt shadow  */
+		if (nested_exit_on_intr(svm))
+			return false;
+	} else {
+		if (!(kvm_get_rflags(vcpu) & X86_EFLAGS_IF))
+			return true;
+	}
+
+	return (vmcb->control.int_state & SVM_INTERRUPT_SHADOW_MASK);
 }
 
 static bool svm_interrupt_allowed(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index f6d604b72a4c..5cc559ab862d 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -386,6 +386,11 @@ static inline bool nested_exit_on_smi(struct vcpu_svm *svm)
 	return (svm->nested.intercept & (1ULL << INTERCEPT_SMI));
 }
 
+static inline bool nested_exit_on_intr(struct vcpu_svm *svm)
+{
+	return (svm->nested.intercept & (1ULL << INTERCEPT_INTR));
+}
+
 static inline bool nested_exit_on_nmi(struct vcpu_svm *svm)
 {
 	return (svm->nested.intercept & (1ULL << INTERCEPT_NMI));
-- 
2.18.2